Study of solar wind discontinuities, their evolution, transport and impact on the near-Earth environment.

这一案例研究的目的是解决关于日冕物质抛射形式的太阳喷发和导致行星际激波的持续高速太阳风区域如何与太阳系天体相互作用的长期问题。该项目的目的将是研究太阳风不连续的质量、能量和动量，它们的传输特性，以及它们对近地系统的影响。这将利用SOHO和STEREO任务目前提供的一套独特的日光层监测数据。利用ACE和Wind航天器对L1的太阳风进行上游监测将提供局部的现场诊断。由四个航天器组成的集群飞行任务将在太阳风驱动因素及其对近地系统的影响之间提供独特的联系，这是通过包括EISCAT和SuperDARN在内的地面仪器测量的。该项目将特别研究：1)静风效应：太阳风中的不连续对磁层的影响是未知的，这是由于日光层等离子体片中分离的等离子体斑点造成的。STEREO将首次对太阳风密度最高的太阳附近的结构进行详细测绘。利用集群航天器以及WIND和ACE航天器对这些结构进行多点研究(平面定向、间断诊断)，将有助于详细分析这些结构的演变。对不连续性对磁层的影响进行系统分析将有助于更好地理解磁层活动的平静时间驱动因素。2)瞬变研究：首次可以使用HI相机和1个AU航天器阵列(星系团、ACE、WIND)研究日冕物质抛射的二维结构。日冕物质抛射前后通量管的取向将与日冕物质抛射的径向密度演化进行比较。HI相机将被用来确定我们在瞬变的前方的位置，并了解安静时间的行星际通量管是如何被压缩并滑到瞬变的前面的。3)瞬变的影响：直接观测瞬变及其与弓激波相互作用时覆盖在地球磁层上的二维结构，将是对确定太阳风扰动对磁层的“地缘有效性”的机制的第一次详细分析。星团航天器将与ACE、双星、EISCAT和SuperDARN相结合，用于研究磁层对HI相机中看到的单个密度波动和撞击结构内的湍流的反应。根据这些活动的进展情况，这项工作可扩展到：i)解释太阳风与具有内在磁场的太阳系天体(如近地和土星系统)与非磁化天体(如金星、火星和彗星)相互作用之间的差异。这将是参与机构内部已经开展的一些前期工作的后续工作。二)建立必要的理论模型，以显示太阳事件对日球层系统的传播、物理过程、相互作用和影响，目的是帮助预测这类事件的影响。

This CASE studentship is targeted at addressing long-standing questions on how the solar eruptions in the form of Coronal Mass Ejections (CMEs) and regions of sustained high speed solar wind resulting in the interplanetary shocks, Corotating Interaction Regions (CIRs), interact with solar system bodies. The aim of the project will be to study the mass, energy and momentum of solar wind discontinuities, their transport characteristics, and their impact on the near-Earth system. This will make use of access to the unique set of heliospheric monitoring data available at this time from the SOHO and STEREO missions. Upstream monitoring of the solar wind at L1 with the ACE and Wind spacecraft will provide localised in-situ diagnostics. The four-spacecraft Cluster mission will provide the unique linkage between the solar wind drivers and their impact on the near-Earth system as measured by ground based instrumentation, including EISCAT and SuperDARN. In particular the project will investigate: 1) Effect of quiet-wind: The effect on the magnetosphere of discontinuities in the solar wind due to detached plasma blobs in the heliospheric plasma sheet is unknown. STEREO will allow the first detailed mapping of these structures close to the Sun where the solar wind density is highest. Multipoint studies of these structures (plane orientation, discontinuity diagnostic) using the Cluster spacecraft as well as the WIND and ACE spacecraft will facilitate detailed analysis of the evolution of these structures. A systematic analysis of the effect of discontinuities on the magnetosphere will lead to a greater understanding of the quiet-time drivers of magnetospheric activity. 2) Study of transients: The study of the 2-D structure of CMEs will for the first time be possible using the HI cameras and the array of 1 AU spacecraft (Cluster, ACE, WIND). The orientation of flux-tubes ahead, inside and behind CMEs will be compared to the radial density evolution of CMEs. The HI cameras will be used to define our location on the front of the transient and to understand how quiet-time interplanetary flux-tubes are compressed and slip ahead of the transient. 3) Effect of transients: Direct observation of the 2-D structure of transients and their draping over the Earth's magnetosphere as they interact with the bow shock will be the first detailed analysis of the mechanisms that determine the 'geo-effectiveness' of solar wind disturbances on the magnetosphere. The Cluster spacecraft combined with ACE, Double Star, EISCAT and SuperDARN will be used to study the response of the magnetosphere to individual density fluctuations seen in the HI cameras and the turbulence within the impinging structure. Depending on the progress of these activities the work may extend to: i) Explaining the differences in the interactions between the solar wind interactions with solar system bodies with intrinsic magnetic field (such as near Earth and Saturnian systems) and those of non-magnetised bodies (such as Venus, Mars and comets). This will follow on from some preliminary work already underway within the participating institutes. ii) Developing the theoretical models necessary to demonstrate the propagation, physical processes, interactions and impact that solar events have on the heliospheric system, with the aim to help in the forecasting of the impact of such events.